When you finish work for the day and head for home, you may assume you can say whatever you want online. You’re not posting on your employer’s time, after all, and your Facebook, Twitter, Instagram or Snapchat profile is private, right? Wrong.

Nothing you post on social media is ever truly private. By design, most social media platforms allow for sharing by your friends, or even strangers, and a single post can reach thousands of people before you know it. If you have second thoughts and delete something, if someone takes a screen shot that post can haunt you.

“The term ‘going viral’ is an apt description, as words online can spread like an infection,” says Charles Thompson, who practices employment and labour law at Burchell MacDougall LLP’s Truro office, “You need to assume that anything you post online could end up in your boss’ inbox.”

Many employers are catching up to the popularity of social media among their employees. If you signed an employment contract when you started your job, it probably contained a code of conduct, and possibly even specific rules around social media posting.

“What you may consider to be a private rant about your employer, client or customer can spread beyond your circle of friends,” Charles explains, “and your momentary outburst can cause damage to a company’s reputation. The courts are now recognizing this.”

Consider the case of two workers at a detailing shop in British Columbia, who were fired in 2010 for airing workplace grievances on Facebook. Some posts threatened violence to an unknown man presumed to be the company manager, while others merely complained about the workload. The Labour Relations Board considered the posts threatening, insubordinate, and ultimately contributing to a hostile work environment, and upheld their terminations.

A post by an employee expressing offensive personal opinions or beliefs, even without any mention of their employer, can still result in termination.

“In 2014, Toronto firefighters were fired for racist and sexist remarks made on Twitter,” Charles goes on, “and an arbitrator agreed their dismissal was appropriate. While the comments had nothing to do with the employees’ jobs, they reflected poorly on the Toronto Fire Service and harmed their ability to recruit women and minorities.”

Charles also warns against writing disparaging posts on blogs and websites, as so-called ‘anonymous’ comments can be traced back the poster through IP addresses and other means, and could have negative consequences.

For example, in 2010, the Nova Scotia Supreme Court ordered a newspaper and Google to disclose the identity of two individuals who posted anonymous disparaging comments online about the chief and deputy chief of the Halifax Fire Service, to enable them to pursue legal action. The judge stated she would make the order “because the court does not condone the conduct of anonymous internet users who make defamatory comments and they, like other people, have to be accountable for their actions.”

So, if you’ve had a bad day at work, stop and think before posting a ‘my boss is a total idiot’ rant on social media; ask yourself if it’s something you would want them to read, and consider whether or not it’s worth jeopardizing your job.

This article is for information only and is not intended to be legal advice. If you have any questions or would like further information, you should consult a lawyer.